>> thanks so much, jim. >>> now from boston, we turn to breaking news we have at this hour. a letter addressed to a united states senator was intercepted, found to contain a deadly poison. the news is still coming in and pierre thomas has all the late-breaking details right now out of washington. pierre? >> tonight the senate is on high alert after a letter bound for one of its members was intercepted because it may have been tainted with poison. sources are telling us tonight a letter addressed to mississippi senator roger wicker tested positive for ricin in a field test in maryland. the letter was post marked memphis, tennessee. tonight there's no information on who may have sent it. ricin is der reiffed from caster beans and can be lethal if ingested or inhaled. field tests to detective it are unreliable. a source tells us the letter is tested again in a laboratory to get a definitive result. the package was intercepted and never reached the capital complex. still, additional security is being put in place. all mail to capitol hill has been stopped. such scares have happe